While the present invention is subject to a wide range of applications, it is particularly suited for autonomous or robot type vehicles which are intended to operate and to navigate independently under computer control and in particular to improvements in the drive and steering design for these vehicles.
During autonomous navigation of vehicles in constrained spaces, it is highly desirable for them to have the ability to move and rotate in any direction. This ability is particularly important in indoor spaces. Further, there are instances in which it is desirable to provide these vehicles with the ability to move without rotation or to turn without translation because of external constraints. Also, vehicles with preferred direction of motion required by factors such as placement of sensors, arms or other tooling, are preferably able to translate sideways without rotating. Moreover, it is desirable to enable vehicles to rotate about an arbitrary point in confined spaces.
In the past, a number of vehicles have incorporated a plurality of caster wheels positioned around the outer edge of the vehicle body and surrounding a driving and possibly steering wheel. Examples of this type of construction are disclosed in U.S. Pat. Nos. 3,700,058; 3,876,026; 3,938,608; and 4,694,923.
However, none of these patents disclose a system which can be relatively easily controlled to determine the position and orientation of the vehicle, provide solid directional control, and develop adequate friction with the running surface.
U.S. Pat. No. 4,221,273 to Finden relates to a steerable and motor driven vehicle with a single vertical center axis about which the driving wheels are rotated. By contrast, the present invention incorporates two separate traction wheels which are steered by a steering motor about separate axes.
It is a problem underlying the present invention to provide a vehicle which can be relatively easily steered and driven under computer control.
It is an advantage of the present invention to provide a vehicle which obviates the limitations and disadvantages of the prior art.
It is a further advantage of the present invention to provide a vehicle which has the ability to execute arbitrary radius turns.
It is a still further advantage of the present invention to provide a vehicle which can execute zero radius turns.
It is a yet further advantage of the present invention to provide a vehicle for lateral translation with fixed orientation in any direction from a point.
It is a still further advantage of the present invention to provide a vehicle with conventional wheels having the ability to rotate about an arbitrary point at any position and at any distance from the vehicle.
Accordingly, there has been provided a vehicle constructed of a first load-carrying frame having freely rotable supporting wheels attached thereto. A second frame is non-rotably and compliantly suspended from the first frame. A device is mounted to the second frame for driving and steering the vehicle.